Bringing new insights to Central North Sea with OBN and FWI imaging

Spanning decades of exploration and production in the United Kingdom Continental Shelf, many programs of towed streamer data have shaped our knowledge of the Central North Sea. However, the fundamental lack of illumination and azimuth/offset coverage provided by towed streamer geometries, remains a blocker to resolving the imaging challenges associated with many higher-risk Jurassic and Triassic plays. This means that existing streamer data is rapidly approaching the limit in the value it can add to our understanding of this mature basin. The Cornerstone ocean bottom node (OBN) program looks at using the well-known benefits of OBN data; full azimuths, long offsets and rich low frequencies, to provide a step change in imaging of this important region of the North Sea. This is achieved through improved model building, in particular the detail unlocked by full waveform inversion using the latest Time Lag cost function ( Zhang et al.,2018 ).Utilizing TL-FWI on this OBN data aimed at improving the entire section of the velocity model: the complex overburden, intra chalk and sub-chalk layers. In addition to the added illumination achieved from OBN data, the use of the multiples, further illuminates areas of the subsurface not captured in the primary wavefield.